The goal of this grant is to test the hypothesis that hESCs and iPSCs acquire specific metabolic signatures important for stemness through a common means, possibly by an exposure to stabilized HIF activity. Recent data support this hypothesis; HIFs have shown to play a role in ESC fate and ESCs have shown to sustain highly unsaturated metabolome. However, it is not yet clear how ESCs acquire their metabolic state, how the state is maintained and further, how the metabolic state of differentiation is obtained. We have showed that hypoxia is involved specifically in the acquisition state of stemness since hypoxia alone can de-differentiate committed cells back to stem cell fate. The de-differentiated cells re-activate Oct4 promoter analyzed by Oct4- GFP. These hypoxia induced stem like cells also mimic hESCs by their colony morphology, long-term self- renewal capacity, capability to replicate both in hypoxia and normoxia, genome wide mRNA and miRNA profiles, cell surface marker, TRA1 and SSEA expression and capacity to form teratomas. Furthermore, we have observed a specific metabolic signature in ESCs. We will now test whether hypoxia induced transcription factor, HIF is sufficient to induce the ESC specific metabolic pattern. We will first analyze glycolytic and oxidative phosphorylation responses to hypoxia using a panel of stem cells with different stages of pluripotency (piSC, diSC, EpiSC, HiPSC) and differentiated cells, followed by detailed assessment of redox poise within the mitochondrial electron transport chain (ETC) and metabolic pathway flux. Secondly, we will define the contribution of HIF activity for induction of unique stemness signatures (metabolism, mtDNA copy number) using hypoxia de-differentiation paradigms (HiPSC). Paradoxically, hypoxia has shown to affect both stemness and differentiation, suggesting that HIF might be differentially regulated to obtain the desired cellular outcomes. Therefore, we will devise high throughput screens to identify molecules that specifically affect HIF- induced stemness by promoting or interfering with stem cell-associated metabolic pathways. These studies will beget a new level of understanding of the acquisition of stemness and cancer and as such are bound to result in new approaches both in re-generative and cancer medicine.